Wood grinder



Feb. 19 1924'.

W. THALER WOOD GRINDER Filed Aug. 15, 1921 2 Sheets-=Sheet 1 ATTORNEYS Feb. 19 1924. 1,484,585

W. TH; ALER WOOD GRINDER Filed Aug. 15 1921 2 Sheets-Sheet 2 INVENTOR WILH'ELM THMLER ATTORNEYS Patented Feb. l9, llQZl.

entrain stares teases WILHELBE TERI, 0F HEIDENHEIM-ON-THE-BRENZ, GERMANY.

WOOD GRINDER.

Application filed. August 15, 1921. Serial No. 492,485.

To all whom it may concern:

Be it known that I, lVILHELM THALER, a citizen of the Republic of .Wurttemberg, Germany, residing at Heidenheim-on-the- Brenz, Germany, have invented certain new and useful Improvements in Wood Grinders, of which the following is a specification.

vMy invention relates to wood grinders provided with presses of the fluid pressure type, i. e. in which the press plungers or their equivalent are driven by hydraulic or pneumatic power. The object of my invention is to provide means for automatically controlling the distribution of the power from a common source to the several presses of a group in order to secure their advance at uniform, speed during their working strokes in spite of variations in resistance offered by the charges upon which the several presses operate. A product of greater uniformity is thus obtained.

It is a well recognized defect of the present wood grinders which employ hydraulic or pneumatic plungers for pressing the wood billets against the grindstone, that although the pressure on the plungers is constant, the pressure of the wood against the grindstone varies by reason of the fact that the billets of wood take different positions in the pressure chamber, and while some bind or stick against the walls of the chamber, others are free. The consequence is that where, as is common practice, a group of cylinders is connected to a common source of power, some plungers will press the wood against the stone with less force than others, by reason of the difierent frictional resistance encountered in the several pressure chambers. The product is therefore non-uniform since the difference in advance of the press plungers results in difference in filber length and fineness of the yield from the several plunger cylinders.

By the present invention means are provided for varying the pressure in the several cylinders, as necessary, to overcome the internal frictional resistance of the wood blocks in the pressure chambers and to feed the plungers forward at a substantially uniform rate, thus securing a substantially uniform product. The invention is susceptible of various embodiments, some of which are illustrated in the accompanying more or less dia ammatic drawin s, in which F i gs. 1, 2, t, 5 an 6 are diagrammatic vertical sections through multiple cylinder grinders in which the invention is embodied in different manners; and

Fig. 3 is an enlarged, vertical section through a regulating valve used in certain of the constructions. 1

Referring to Fig. 1, in which these pressure cylinders P, P and P are associated with a. single grindstone, the pressure ducts leading to the several cylinders from the main (connected to the pump A or other source of pressure, and having a governor R driven by the axle of the grindstone) are provided with throttle valves'D, l) and D respectively. These valves can be regulated by screwing them up or down, and cause a corresponding drop of pressure in the cylinders P etc. with respect to the power source A.

When the frictional resistance of the wood billets in the several pressure chambers is the same, the power required to force the wood at uniform pressure against the grindstone is equal in each cylinder; the flow of pressure fluid to each cylinder is the same. and there is the same drop of pressure to each throttle valve. Should the wood in one chamber become choked, however, the resulting decreased consumption of the pressure fluid by the plunger causes a smaller reduction of pressure at the corresponding throttle valve and thus a higher pressure in the said press cylinder is produced to overcome the increased resistance. Under the higher pressure the stuck press will work somewhat slower than the others, but a possible complete stoppage, as in the past, will not occur. I

When there is lower resistance in one press, as when but a small amount of wood is against the grindstone, there is a tendency. for the plunger to advance rapidly. This is followed by a greater drop of pressure in the throttle valve of this cylinder, which in turn reduces the speed of advance of the plunger.

The throttles D, D etc., may be directly connected up to the governor, as in Fig. 2.

In order to secure greater uniformity in feed, the throttle valves D, D etc., may be so designed that the degree of throttling is influenced by the quantity of pressure-fluid. In Fig. 3 the throttle K is connected to a coil spring F that tends to hold the valve away from its seat V. The pressure-fluid must pass through the small opening 0 in the valve K, so that the pressure of the lit fluid is diminished in the same degree, as the speed of the plunger increases. The pressure above the valve K is greater and tends to close the valve. The spring F is so adjusted that at the normal rate of plunger advance, a certain drop of pressure is produced. If a plunger advances at lower speed, then thereis produced a higher than normal pressure under the valve K; it is raised andthe valve admits to the cylinder a higher pressure to overcome the increased resistance. When the advance of the plunger is too rapid there isa corresponding closing of the valve and the pressure is diminished' A still greater uniformity in feed of the individual presses is attained by controlling the throttles D, D etc., through the pressblocks, as shown diagrammatically for a two-press combination in Fig. 4. The throt tle members D, D, etc., are connected with the corresponding plungers P, P by the rods a 0,,- and a 0 At the inner end of each rod is attached at b and b a regulator R of any kind which shifts the rod at a speed suited to any given press feed rate. In the drawing, for instance, the regulator or governor acts with its friction wheel aon a friction ring on the disc 0 fast on the shaft of the worm f, which in turn meshes with the worm wheel driving the friction discs 9, g, and through the latter imparts to the rods h, h a'feed commensurate with the normal feed of the presses. The rods h, k are connected through the link system a, a 6', b and 0, 0 to the stems of the regulating valves and thus control the positions of the latter. If both presses P and P move at the chosen speed, then the points 0,, 0 remain at rest, the throttling in D and D continuing unchanged. Should one of the presses lag behind for any reason, the link connection a or a advances taf'dily, while the opposite end con nection b or b lifts more rapidly in view of the continued drive. Consequently the connection at 0 or 0 to the regulating valve is lifted and the valve D or D is opened. Vice versa, if the press advances too fast. The rods h and h are driven by friction at g, g, so that when the presses are re- .versed they return without difficulty.

' Fig. 5 displays a developed example of the scheme of Fig. 4, for a three-cylinder grinder. In this case the throttle members D' D D areregulated by the differential dnves a 6 '0 a b c and a 6 0 The gears or friction dlSkS- b b 6 are actuated by an adjustable drive (I, e, 7, set to the mean feed rate of the pressesP', P P The gears or friction disks a a,, a are actuated by the movement of the plunger toward the grindstone through driving bands or chains g, g 9 When (1,. 6 have an equal circumferential velocity, (aand b rotating in opposite directions) then 0, remains at rest. If the plunger P moves slower than the mean feed speed, then 0 is turned upward by the greater circumferential velocity of b, on a, and the throttle member D- is opened wider. When the press moves faster, 0, is correspondingly moved downward and D is closed somewhat.

The rate of average feed may be con trolled by means of any form of governor.

The regulation of the pressure and of the quantity of pressure fluid in the several press cylinders can be effected in various ways. For example, in Fig. 6 each press P, P", P receives its pressure fluid from a separate pressure pump D, D D the latter being so driven that their deliveries are alike. Besides the'pump may be subject to common control by a governor R driven by the grind stone and in turn actuating a variable drive K. Thus the pressure in the individual pumps varies automatically with the resistance of the corresponding presses.

I claim:

1. Wood grinding apparatus comprising grinder means, a plurality of associated presses, a common source of pressure for the latter, and means automatically and individually governing the delivery of power from said pressure source to the several presses to maintain the advance of the charges thereby substantially uniform regardless of variations in individual power demand for this purpose.

2. Wood grinding apparatus comprising grinder means, a plurality of associated presses, a common source of pressure for the latter, and means automatically responsive to the varying demanus of the several presses, to distribute power from said pressure source individually to the several presses, to secure their substantially uniform advance toward the grinder means.

3. Wood grinding apparatus comprising a grinder, a series of presses for pressing wood against the grinder, a common source of pressure therefor, and means automatically responsive to the varying demands of the several presses, to distribute the power from said pressure source individually to the several presses in accordance with the assesses 5. Wood grinding apparatus comprising grinder means, a series of presses for pressmg wood against the grinder means, a common source of fluid pressure therefor, a main pressure duct connected to said source, branch ducts leading from the main duct to the several presses, and a throttle in each of the branch ducts for automatically controlling the flow of pressure fluid therethrough in accordance with the demands of its associated press, said throttles serving to so distribute the pressure fluid that the advance of the several presses is substantially uniform.

6. Wood grinding apparatus comprising grindermeans, a series of presses for pressing wood against the grinder means, a common source of fluid pressure therefor, a main ressure duct connected to said source,

ranch ducts leading from the main duct to the several presses, and a cushioned throttle in each of the branch ducts for automatically controlling the flow of pressure fluid therethrou h in accordance with the demands of its associated press, said throttles serving to so distribute the pressure fluid that the advance of the several presses is substantially uniform. I

7. Wood grinding apparatus comprising 'nder means, a series of resses for press- 111g wood against the grin er means, a common ,source of fluid pressure therefor, a main pressure duct connected to said source, branch ducts leading from the main duct to the several presses, and a throttle in each of the branch ducts for automatically controlling th-w of pressure fluid therethrough in accordance with the demands of its assoflow of pressure fluid in the main pressure duct.

8. Wood grinding apparatus comprising a grinder, a plurality of feed chambers associated with the inder, a press plunger working in each c amber, a pressure cylinder for each plunger, a source of fluid pressure, a main pressure duct connected thereto, a branch duct from each of the pressure cylinders to the main pressure duct, and a throttle in each of said branch ducts for automatically controlling the Eadmi'ssion of pressure fluid to its associated pressure cylinder to maintain the advance of the several press plungers substantially uniform during their working strokes.

9. Wood grinding apparatus comprising grinder means, a series of presses for pressmg wood against the grinder means, a common source of fluid pressure, a separate duct leading to each press from said common source of pressure, and a throttle in each duct, said throttle comprising a valve spring-pressed from its seat, and a restricted passage through said valve for the flow of fluid pressure past the valve to the associated press. 4

In testimony whereof I have signed my name to this specification.

- WILHELM THALER. 

